FIELD OF THE INVENTION
This invention is directed to a system for suppressing false resolution alerts to be combined with an air traffic alert collision avoidance system (TCAS). In particular, this invention is directed to a horizontal miss distance filter employing a parabolic range tracker to provide projected range, projected range rate and projected range acceleration. The projected range acceleration is utilized to distinguish non-zero horizontal miss distance encounters for which a false resolution alert may be potentially generated. Still further, this invention directs itself to a system which further evaluates encounters having non-zero miss distances to determine whether an estimated horizontal miss distance is sufficiently large to not be a collision threat, thereby warranting suppression of a resolution alert. Additionally, a bearing based tracker is utilized to formulate a horizontal miss distance based on bearing information provided by the TCAS system, with the smaller of the range based horizontal miss distance or bearing based horizontal miss distance being utilized to determine whether the intruder aircraft poses a collision threat. Further, in order to avoid mistakenly inhibiting a resolution alert, maneuver detection logic is incorporated into the horizontal miss distance filter to prevent inhibiting resolution alerts when maneuvers are detected.